Method of preparing pulp.



UNITED STATES PATENT OFFICE.

CARL BACHE-WU'G, OF BERLIN, NEW HAMPSHIRE, ASSIGNOB OF ONE-HALF TO HUGH J. CHISHOLM, OF NEW.YORK, N. Y.

METHOD OF PREPARING PULP.

No Drawing.

To all whom it may concern:

Be it known that I, Cant. BAoHE-VViiG, a citizen of the United States, residing at Berlin, in the county of Coos and State of New Hampshire, have invented an Improvement in Methods of Preparing Pulp, of which the following is a specification.

This invention has for its object the production of pulp by a novel method from straw, cornstalks and similar substances, which is suitable for use as a substitute for ground wood pulp, and may be used as ground wood pulp is now used in the manufacture of paper, as for example, in the manufacture of news-print paper, which pulp compares favorably with ground Wood pulp in quality and in cost of production. My new method, however, is also adapted for wood and similar cellulosic substances.

My new method involves confining the cellulosic substance to be treated, usually in small pieces, or blocks, in a digester, then withdrawing the air from them, thereby producing a vacuum, in the digester, or, more strictly speaking, a partial vacuum, then pressingin sulfurous gas such as sulfur dioxid, (S0 to bleach the pieces and to soften but not destroy the ligncous matter, then injecting a solution of sodium chlorid (NaCl) and cooking the mass; or, in lieu of employing a solution of sodium chlorid, a bi'sulfite liquor may be employed, but for ordinary purposes the solution of sodium chlorid is preferable, as it is well suited for the attainment of the desired result, 2'. e., retention of the ligneous matter, although its character is probably modified, but its weight is not substantially reduced. Whether the cellulosic substance employed be straw, cornstalks or wood, I have discovered that when the air is withdrawn from it, a bleaching and softening gas may be pressed into intimate contact with the fibers composing it in such manner as to bleach them and also to soften but not to destroy the ligneous matter by which they are naturally bound together. The sulfurous or other gas may be pressed in say for one or two hours. The

mass may be cooked in a solution of sodium.

chlorid for say two or three hours, which is usually sufficient, although it may be cooked for a longer or shorter period of time, according to the quality or grade of pulp which it is desired to produce. A finer Specification of Letters Patent.

Patented Jan. 13, 1914.

Application filed December 5, 1912. Serial No. 735,196.

quality of pulp may be produced by longer cooking. If a bisulfiteliquor is employed in lieu of a solution of sodium chlorid the stock will be cooked for about the same length of time, and the resulting product will be a still higher quality of pulp. The expense of such treatment increases the cost of production. When the stock has been treated in accordance with my method it is washed, and if used as a substitute for ordinary ground wood pulp in the manufacture of news-print paper, further bleaching will not be required, but if it is desired for use for finer grades of paper it may be further bleached by a sulfurous gas or other bleaching agent. If used for news-print paper the stock when washed will be subjected to the action of a kollergong, disintegrator, grinder or, refiner and then screened, as usual in the treatment of wood pulp. The resulting product when cooked in a solution of sodium chlorid is not cellulose, but is what might be termed a half cellulose, yet if cellulose is desired which is suitable for the finer grades of paper a bisulfite liquor will be employed and the stock will be cooked for a longer period of time.

The novel steps in my process consist in withdrawing the air from the cellulosic substance to be treated and then pressing in a bleaching and softening gas, thus to prepare the stock for cooking.

I claim 1. The method herein described of treating straw, cornstalks and other cellulosic substances to prepare a stock suitable for use as a substitute for ground wood pulp, which consists in confining the cellulosic substance in a digester, withdrawing the air from it, pressing into it a gas by which it is bleached and the ligneous matter softened, then injecting a pulp-forming liquor and cooking the mass.

2. The method herein described of treating straw, cornstalks and other cellulosic substances to prepare a stock suitable for use as a substitute for ground Wood pulp and containing ligneous matter, which consists in confining the cellulosic substance in a digester, withdrawing the air from it, pressing into it sulfur dioxid by which it is bleached and the ligneous matter softened but not. destroyed, then injecting a pulpforming liquor and cooking the mass.

but not destroyed, then injecting a solution 19 of sodium chlorid and cooking the mass.

In testlmony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses. N

CARL BACHE-WUG. \Vitnesses:

W. H. PAINE, JOHN BAoHE-Wtic.

[SEAL] Pulp, was erroneously written and printed as Letters Patent should be read with thi It is hereby certified that the name of the patentee in Letters Patent No.

1,084,244, granted January 13, 1914, for an improvement in' Methods of Preparing Carl Bache-Wiig, Whereas said name should have been written and printed as Carl Bache Wi/Lg; and that the said 5 correction therein that the same may conform to the record of the case in the Patent Oflice. Signed and sealed this 3rd day of July, A. D., 1917.

F. W. H. CLAY,

Acting Commissioner of Patents. 

